Great Plains NP30A 30-foot Operator Manual - Manual (Page 99)

Great Plains Manufacturing, Inc. Table of Contents Index Adjustments 95
2014-05-20 Table of Contents Index 407-502M
Knife Adjustment
Refer to Figure 77
Knives have no adjustments. Application depth is set by
the tool bar (page 91).
Knives have (Grade 5) shear bolts . Should the knife
encounter a substantial obstruction, such as a large
rock, or if speed plus conditions are too challenging, the
shear bolt fails, and the knife swings back on the
(Grade 8) mounting bolt
.
A shear usually results in the need to replace all of:
802-038C
HHCS 1/2-13X2 1/4 GR5
803-020C NUT HEX 1/2-13 PLT
804-015C WASHER LOCK SPRING 1/2 PLT
804-094C WASHER FLAT 1/2 HARD ASTMF436
Inspect tubing connections to the knife whenever
replacing a shear bolt.
Ammonia Exposure Hazard:
Discharge the system (page 110) before replacing a shear bolt.
Bolt replacement requires raising the applicator. Minimize
your vapor exposure. If shears are frequent, application may
be too deep, or the soil conditions too rough. Even with
cautious system discharges, your accumulated ammonia
exposure could exceed PEL and lead to health problems or
injury.
Ammonia Exposure Hazard:
Do not back up with knives in ground to realign a knife for bolt
replacement. This will plug outlets on other knives.
If
1 ⁄
2
-13 Grade 5 bolts are not immediately available,
temporarily substitute metric M12
×1 Class 8.8.
Spring Shanks
Refer to Figure 78
If applicator is equipped with spring shanks (optional
item) the spring should be compressed to measure:
11
1 ⁄
4
inch to 11
3 ⁄
8
inch (28.6 to 28.9 cm)
once mounted. The distance is measured from end of
spring to end of spring.
Note: When encountering substantial obstructions in the
field, spring shanks help alleviate stress on the
knife shear bolt. Spring shanks reduce, but do not
eliminate all shear bolt failures.
Equipment Damage Risk:
Do not use a bolt strength higher than Grade 5, or
obstructions can result in machine damage. Using less than
Grade 5 results in nuisance shears.
Figure 77
Knife Shear Bolt
31593
6
7
6
7
Figure 78
Spring Shank
36006
6
8
8